3 files changed, 29 insertions, 9 deletions

diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
index a393f93390a2..482219fb4db2 100644
--- a/drivers/gpu/drm/vc4/vc4_crtc.c
+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
@@ -852,11 +852,19 @@ void vc4_crtc_destroy_state(struct drm_crtc *crtc,
 
 void vc4_crtc_reset(struct drm_crtc *crtc)
 {
+	struct vc4_crtc_state *vc4_crtc_state;
+
 	if (crtc->state)
 		vc4_crtc_destroy_state(crtc, crtc->state);
-	crtc->state = kzalloc(sizeof(struct vc4_crtc_state), GFP_KERNEL);
-	if (crtc->state)
-		__drm_atomic_helper_crtc_reset(crtc, crtc->state);
+
+	vc4_crtc_state = kzalloc(sizeof(*vc4_crtc_state), GFP_KERNEL);
+	if (!vc4_crtc_state) {
+		crtc->state = NULL;
+		return;
+	}
+
+	vc4_crtc_state->assigned_channel = VC4_HVS_CHANNEL_DISABLED;
+	__drm_atomic_helper_crtc_reset(crtc, &vc4_crtc_state->base);
 }
 
 static const struct drm_crtc_funcs vc4_crtc_funcs = {
diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index 8c8d96b6289f..90b911fd2a7f 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -532,6 +532,8 @@ struct vc4_crtc_state {
 	} margins;
 };
 
+#define VC4_HVS_CHANNEL_DISABLED ((unsigned int)-1)
+
 static inline struct vc4_crtc_state *
 to_vc4_crtc_state(struct drm_crtc_state *crtc_state)
 {
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index af3ee3dcdab6..149825ff5df8 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -616,7 +616,7 @@ static int
 vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
 {
 	unsigned long unassigned_channels = GENMASK(NUM_CHANNELS - 1, 0);
-	struct drm_crtc_state *crtc_state;
+	struct drm_crtc_state *old_crtc_state, *new_crtc_state;
 	struct drm_crtc *crtc;
 	int i, ret;
 
@@ -629,6 +629,8 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
 	 * modified.
 	 */
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		struct drm_crtc_state *crtc_state;
+
 		if (!crtc->state->enable)
 			continue;
 
@@ -637,15 +639,23 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
 			return PTR_ERR(crtc_state);
 	}
 
-	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
-		struct vc4_crtc_state *vc4_crtc_state =
-			to_vc4_crtc_state(crtc_state);
+	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+		struct vc4_crtc_state *new_vc4_crtc_state =
+			to_vc4_crtc_state(new_crtc_state);
 		struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
 		unsigned int matching_channels;
 
-		if (!crtc_state->active)
+		if (old_crtc_state->enable && !new_crtc_state->enable)
+			new_vc4_crtc_state->assigned_channel = VC4_HVS_CHANNEL_DISABLED;
+
+		if (!new_crtc_state->enable)
 			continue;
 
+		if (new_vc4_crtc_state->assigned_channel != VC4_HVS_CHANNEL_DISABLED) {
+			unassigned_channels &= ~BIT(new_vc4_crtc_state->assigned_channel);
+			continue;
+		}
+
 		/*
 		 * The problem we have to solve here is that we have
 		 * up to 7 encoders, connected to up to 6 CRTCs.
@@ -674,7 +684,7 @@ vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
 		if (matching_channels) {
 			unsigned int channel = ffs(matching_channels) - 1;
 
-			vc4_crtc_state->assigned_channel = channel;
+			new_vc4_crtc_state->assigned_channel = channel;
 			unassigned_channels &= ~BIT(channel);
 		} else {
 			return -EINVAL;